Add test for Etherbone

Files copied directly from https://github.com/enjoy-digital/sayma_test @ 9ec62242659910ad1726beb00ff15b3f0a406615

artiq/gateware/test/serwb/test_etherbone.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+
+from litex.gen import *
+
+import sys
+sys.path.append("../../gateware/")
+
+from amc_rtm_link import packet
+from amc_rtm_link import etherbone
+
+from litex.soc.interconnect.wishbone import SRAM
+from litex.soc.interconnect.stream import Converter
+
+
+class DUT(Module):
+    def __init__(self):
+        # wishbone slave
+        slave_depacketizer = packet.Depacketizer(int(100e6))
+        slave_packetizer = packet.Packetizer()
+        self.submodules += slave_depacketizer, slave_packetizer
+        slave_etherbone = etherbone.Etherbone(mode="slave")
+        self.submodules += slave_etherbone
+        self.comb += [
+            slave_depacketizer.source.connect(slave_etherbone.sink),
+            slave_etherbone.source.connect(slave_packetizer.sink)
+        ]
+
+        # wishbone master
+        master_depacketizer = packet.Depacketizer(int(100e6))
+        master_packetizer = packet.Packetizer()
+        self.submodules += master_depacketizer, master_packetizer
+        master_etherbone = etherbone.Etherbone(mode="master")
+        master_sram = SRAM(1024, bus=master_etherbone.wishbone.bus)
+        self.submodules += master_etherbone, master_sram
+        self.comb += [
+            master_depacketizer.source.connect(master_etherbone.sink),
+            master_etherbone.source.connect(master_packetizer.sink)
+        ]
+
+        # connect core directly with converters in the loop
+        s2m_downconverter = Converter(32, 16)
+        s2m_upconverter = Converter(16, 32)
+        self.submodules += s2m_downconverter, s2m_upconverter
+        m2s_downconverter = Converter(32, 16)
+        m2s_upconverter = Converter(16, 32)
+        self.submodules += m2s_upconverter, m2s_downconverter
+        self.comb += [
+        	slave_packetizer.source.connect(s2m_downconverter.sink),
+        	s2m_downconverter.source.connect(s2m_upconverter.sink),
+        	s2m_upconverter.source.connect(master_depacketizer.sink),
+
+        	master_packetizer.source.connect(m2s_downconverter.sink),
+        	m2s_downconverter.source.connect(m2s_upconverter.sink),
+        	m2s_upconverter.source.connect(slave_depacketizer.sink)
+        ]
+
+        # expose wishbone slave
+        self.wishbone = slave_etherbone.wishbone.bus
+
+def main_generator(dut):
+    for i in range(8):
+        yield from dut.wishbone.write(0x100 + i, i)
+    for i in range(8):
+        data = (yield from dut.wishbone.read(0x100 + i))
+        print("0x{:08x}".format(data))
+
+dut = DUT()
+run_simulation(dut, main_generator(dut), vcd_name="sim.vcd")